The 3rd Generation Partnership Project (3GPP), which is a standardization project, standardized the Evolved Universal Terrestrial Radio Access (hereinafter, referred to as E-UTRA), in which high-speed communication is realized by adopting an Orthogonal Frequency-Division Multiplexing (OFDM) communication scheme and flexible scheduling using a unit of prescribed frequency and time called resource block.
Moreover, the 3GPP discusses Advanced E-UTRA, which realizes higher-speed data transmission and has upper compatibility with E-UTRA. E-UTRA relates to a communication system based on a network in which base station apparatuses have substantially the same cell configuration (cell size); however, regarding Advanced E-UTRA, discussion is made on a communication system based on a network (different-type radio network, Heterogeneous Network) in which base station apparatuses (cells) having different configurations coexist in the same area. In this regard, E-UTRA is also referred to as “LTE (Long Term Evolution)”, and Advanced E-UTRA is also referred to as “LTE-Advanced”. Furthermore, LTE may be a collective name including LTE-Advanced.
A Carrier Aggregation (CA) technique and a Dual Connectivity (DC) technique are specified, in which, in a communication system where cells (macro cells) having large cell radii and cells (small cells) having smaller cell radii than those of the macro cells coexist as in a heterogeneous network, a terminal apparatus performs communication by connecting to a macro cell and a small cell simultaneously (NPL 1).
Meanwhile, NPL 2 studies Licensed-Assisted Access (LAA). According to LAA, a non-allocated frequency band (Unlicensed spectrum) used by a wireless Local Area Network (LAN) is used as LTE. More specifically, the non-allocated frequency band is configured as a secondary cell (secondary component carrier). Connection, communication, and/or a configuration of the secondary cell(s) used as LAA are assisted by a primary cell (primary component carrier) configured to an allocated frequency band (Licensed spectrum). LAA widens a frequency band that is available for LTE, and thus wide band transmission is enabled. In this regard, LAA is used in a shared frequency band (shared spectrum) shared between prescribed operators.